In a typical solar energy system wherein a solar receiver is utilized in conjunction with a plurality of rotatable solar energy reflectors controlled so as to continuously focus solar energy onto the solar receiver, a loss of coolant to the solar receiver due to a coolant pump failure requires that the reflectors be automatically and rapidly defocused to prevent receiver melt down. However, a pump failure is frequently associated with an overall power failure which would also prevent automatic defocusing of the reflector. In that type of power failure, receiver melt down would occur. The present invention solves the above problem by providing a protection means wherein an automatic flow of sufficient coolant will occur to prevent receiver melt down until the reflectors become defocused with respect to the solar receiver due to the earth's rotation.